Railway signaling apparatus



AprilQO, 1943. YOUNG RAILWAY SIGNALING APPARATUS 4 Sheets-Sheet 1 Filed Oct.

r i la [9 IZH? E X i. m p Q, g E #0 K .Wmbe? m m 6 W m/ H H 5 H 4 I Y J 7 0\ /z/ m D. u w w 6 INVENTOR H. S. YOUNG RAILWAY SIGNALING APPARATUS April 20, 1943.

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April 20, 1943. v H: s YOUNG 2,316,929

RAILWAY SIGNALING APPARATUS Filed Oct. 22, 1941 4 Sheets-Sheet s INVENTOR H9121" Foamy HIS A'i'ToRNEY' April 20,1943.

H. s. YOUNG 2,316,929

RAILWAY SIGNALING APPARATUS Filed Oct. 22, 1941 4 Sheets-Sheet 4 SD M 3W Patented Apr. 20, 1943 RAILWAY SIGNALING APPARATUS Henry S. Young, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application October 22, 1941, Serial No. 416,003 10- Claims. (c1. 246-41 My invent-ion relates to railway signaling apparatus, and it has particular reference to the organization of such apparatus into novel and improved railway signaling systems of the class involving light signals having a plurality of signal lamps and incorporating means effective, when a lamp of a signal fails or burns out, to cause such signal to display a more restrictive aspect.

It has been proposed heretofore to provide a signal system wherein a distinctive permissive indication is displayed at the entrance end of an occupied block so that a train may enter such block without stopping, and which system incorporates means for displaying a stop indication if the permissive indication is not displayed when it should be. In a system of this type, shown and described, for example, in United States Letters Patent No. 2,176,707 granted on October 17, 1939, to L. D. Dickinson and D. C. Bettison, it is customary to utilize a doublecaution aspect as the permissive indication, and it is therefore necessary to provide means for detecting a failure of either of the two caution lamps employed since a failure of either lamp, when a signal is conditioned to display its doublecaution permissive indication, would cause the signal to display a single caution or less restrictive approach indication.

An object of my invention is the provision of signal systems of the class described and incorporating novel and improved means for causing a signal to display a more restrictive indication upon failure of either of the two caution lamps comprising a permissive indication.

Another object is the provision, in a signal system of the class described, of means for additionally causing a signal to display a more restrictive indication upon a failure of the lamp constituting the proceed indication.

An additional object is the provision of novel and improved railway signal systems of the type having one signal indication provided by simultaneously energizing two lamps of a plurality of signal lamps.

The above-mentioned and other important objects and characteristic features which will become readily apparent from the following description, are attained in accordance with my invention by incorporating into a signal system which utilizes signals having a plurality of lamps a selected two of which when illuminated provide one indication, two relays one for each of the selected two lamps of a signal, energizing one of the two lamps at times over a circuit including a'winding of one of the two relays and a front contact of the other of the two relays and simultaneously energizing the other of the two lamps over a circuit including a winding of the other relay and a front contact of the one relay, and by providing means for energizing a third lamp of the signal over a circuit including a back contact of either of the two relays when the circuit means for energizing the two lamps of the signal is interrupted due to a failure of the lamp filament of either of the two lamps.

Other features and advantages of my invention reside in the apparatus employed and in the details of the arrangement thereof, as will be made clear in the following description.

I shall describe several forms of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view illustrating one form of apparatus embodying my invention. Figs. 2, 3 and 4' are each diagrammatic views representing modified forms of the apparatus shown in Fig. 1, and also embodying my invention. In each of the several views similar reference characters have been employed to designate corresponding parts.

Referring to the drawings, the reference characters I and la designate the track rails of a stretch of railway track. divided by insulated joints 2 into a plurality of succesive adjoining track sections of which only one section, DE, is represented complete in the drawings. Each section is provided with a track circuit comprising a suitablesource of current, such as a battery 3, connected across the rails at one end of the section and a track relay, designated by the reference character TR with a suitably distinguishing suffix, connected across the rails at the opposite end of the section. The track circuits may, as shown in Fig. 3. be of the neutral type in which battery 3 is constantlyconnected across the rails of the section to supply current of but one relative polarity to the associated. track circuit, or as shown in'Fig. 1, may be of the polarized type in which battery 3 is caused to supply current of one relative polarity or the other to the rails of the section according as the track relay of the section in advance is picked up or released, respectively. The relays employed as track relays in such polarized circuits are, of course, of the polarized type and preferably are of the. well-known retained neutral class arranged to. retain their neutral armatures in the picked-up position during a reversal of current polarity energizing such relays.

Each signal S has associated therewith a transfer relay, designated by the reference character CX of the source.

POR, normally energized from a suitable source of alternating current, such as a generator not shown in the drawings but having its opposite terminals designated by the reference characters BX and OK, and which relay is effective whenif rent, and such relay when released conditions the signal to be operated" from astand-by source of power, such as a battery BS.

Each light-out relay LR has one of its windings normally energized in series with the filament of the associated yellow lamp Y. For example, winding l5 of relay LRI is energized over a circuit extending from terminal BX through front contact 8 of relay POR, resistor 5, winding I5 of relay LRI', the filament of the upper lamp Y (as viewed in the drawing) of signal SE, and front contact 12 of relay POR to terminal CX. Winding l9 of the other light-out relay LE2 is energized over a similar circuit which may be traced from terminal BX'through front contact 8 of relay-FOR, resistor 5, winding 19 of relay LE2, the-filament of the lower lamp Y of signal SE, and front contact [2* of relay FOR to terminal CX. Resistor 5 is selected to have a value such that the current supplied through the resistor to the lamps Y ofsigna'l SE is limited toa value below that required to illuminate the lamps. Winding of relay LRI has connected in multiple therewith an asymmetrical unit 2| arranged to shunt away from the winding onehalf of each wave of the alternating current supplied from the source BX--CX through resistor 5 to the upper lamp Y of signal SE, and winding, l 5 is proportion-ed and adjustedto cause relay LRI to pick up and remain in its-picked-up position in response to the half-wave pulses of current which are supplied through winding l5 to the upper lamp Y. Winding [9 of relay LRZ has, in like fashion, asymmetrical unit 23 connected in multiple therewith, and relay LRZ is I type light-out relays LR to be effectively'energizedfrom a source of alternating current.

Each signal S in Fig. 1 is'controlled by its associated track relay TR in the following manner: When the section in advance is unoccupied so that the advance track relay is picked up to' close its front contacts 6 and 1', current of what I shall term normal polarity is supp-lied from battery 3 to the rails of the associated section to cause the associated track relay to be energized in its normal direction. In this condition of the apparatus, lamp G of signal SE is caused to be illuminated over a circuit extending from terminal BX through front contact 8 of relay POR, front contacts 9 and I8, in multiple, of relay TR-E, polar contact H of relay TRE in its normal or. left-hand position, as viewed in Fig. l, the filament of lamp G of signal SE, and front contact I2 of relay POR to the other terminal Signal SE consequently displays its green aspect to indicate that two blocks,

at least, in advance of the signal, are unoccupied.

When the section in advance of section D-E is. occupied relay TED is released to close its back contacts 6 and l and cause battery 3 to supply current of reverse polarity to the rails of section D-E, whereupon relay TRE is energized in its reverse direction and causes its polar contact member I l to operate to its reverse or righthand position. In this condition of the apparatus, one lamp Y of signal SE is caused to be illuminated over a circuit extending from terminalBX through front contact 8 of relay POR, front contacts 9 and ill, in multiple, of relay TRE, polar contact member ll of relay 'I'RE in its reverse position, upper winding 14 of 'lightout relay LRI, the filament of the upper lamp Y of signal SE, and front contact [2 of relay POR to terminal CX. Asymmetrical unit it is connected across winding I4 of relay LRlso as to shunt one-half of each wave of the alternating current away from the winding. Winding i4 is arranged to cooperate with winding 15 in maintaining relay LRI in its picked-up position, and the resistance of winding I4 is selected to have a value such that the current supplied through winding M to lamp Y is suificient to cause that lamp to be illuminated. Signal SE accordingly is caused to display a single yellow aspect to indicate that the section, next in advance of the section governed by the signal, is occupied.

When section D-E is occupied by a train, relay 'TRE is shunted and its back contacts 9 and I8 close to cause both lamps Y of signal SE to become illuminated. One lamp Y of signal SE is energized over a circuit extending from terminal BX through front contact 8 of relay P'OR, back contact 9 of relay TRE, front contact I! of relay LRI, winding l8 of relay LRZ, the filament of lower'lamp Y of signal SE, and front contact I? of relay POR to terminal CX; while the other lampY of signal SE is energized over a circuit I extending from terminal BX through front contact 8 of relay POR, back contact I 0 of relay one half of each wave of the alternating current away from such relays so asto enable such relays to beenergized by alternating current as well as by direct current. The values of windings l4 and I8 of light-out relays LR'l, and LE2, respectively, are selected to permit both yellow lamps Y of signal SE to be effectively energized and illuminated with the result that signal SE is caused to display a double yellow aspect to in-V dicate that the associated section is occupied,

-It i to be noted that when signal SE is conditioned to display its double-caution: permissive aspect, the circuit of one lamp Y of the signal is carried through a winding of its associated one light-out relay LR and a front contact of the other lightl-out relay, and that the circuit of the other lamp Y of the signal is carried through a winding of the associated other lightout relay LR and a front contact of the one light-out relay, hence it follows that when relay -TRE is released to condition signal SE to display its double-caution permissive indication, relay LRI must be in its picked-up position in order to close its front contact I1 and permit lower lamp Y and winding I8 of relay LR2 to be energized, while relay LRZ must likewise be in its picked-up position in order to close its front contact 20 and permit upper lamp Y and Winding ll of relay LRI to become energized. The utility of energizing the lower windings I5 and I9 of relays LRI and LRZ, respectively, in series with the filaments of lamps Y of signal SE, is now apparent, since these windings hold relays LRI and LRZ in their picked-up positions at all times (provided that the filaments of lamps Y are intact) and hence enable the illuminating circuits of the yellow lamps to be completed when the signal is conditioned to display its double-caution or permissive aspect. It follows, therefore, that if either yellow lamp Y fails or burns out, the associated light-out relay is caused to release to open the circuit of the other yellow lamp, thereby precluding the possibility of signal SE displaying a single yellow aspect when it should be displaying a double yellow aspect.

In the event that a lamp Y of signal SE burns out, lamp R of the signal is then caused to be illuminated over a circuit extending from terminal BX through front contact 8 of relay POR, and then through back contact 9 of relay TRE and back contact I1 of relay LRI, or through back contact I of relay TRE and back contact 20 of relay LRZ, then through the filament of lamp R of signal SE and front contact 8 of relay POR to terminal CX. Signal SE accordingly is caused to display a red aspect which in accordance with the usual custom indicates stop, then proceed, and it follows that when either lamp comprising the permissive indication of signal SE fails or burns out, the signal is then caused to display a more restrictive indication.

Relay POR functions, in accordance with the usual practice, to transfer the operation of signal SE from the alternating current source to the stand-by source, battery BS, in the event of a power failure of the alternating current source. The various asymmetrical units shown in Fig. 1 are so disposed that when relay POR is released to cause signal SE t be transferred to battery operation, the units present their high resistance directions to the flow of current from the battery and hence do not provide shunt paths for current from the battery.

In a modified arrangement, shown in Fig. 2, of the apparatus represented in'Fig. 1, the yellow lamps Y are constantly energized at a level below that required to illuminate the lamps, but ufficient to hold up the light-out relays LR, by current derived from the stand-by battery BS. The upper lamp Y of signal SE, for example, is constantly energized over an obvious circuit extending from one terminal of battery BS through winding l of relay LRI. and the filament of upper lamp Y of signal SE to the other terminal of battery BS. Similarly, lower lamp Y of signal SE is energized over an obvious circuit passing from the one terminal of battery BS through winding I9 of relay LR2, and the filament of lower lamp Y-of signal SE to the other terminal of battery BS. The windings I5 and I9 of relays LR! and LRZ, respectively, are proportioned to have a relatively high resistance of the order sufficient to limit the current flowing through the filaments of lamps Y to a value below that required to illuminate the lamps, but which current has a value sufiicient to effectively energize and cause relays LRI and LR2 to pick up. It follows that as long as the filaments of lamps Y of signal SE are intact, relays LRI and LRZ are energized and occupy their picked-up positions.

An advantage of the apparatus represented in Fig. 2 is that windings I5 and I9 of relays LRI and LRZ, respectively, are energized by unidirectional current, and such windings are proportioned to limit the current flow therein to a value below that required to illuminate the associated lamps Y of the signal. This enables resistor 5 and asymmetrical unitsZI and 23, required for proper operation of the apparatus represented in Fig. 1, to be dispensed with in Fig. 2.

In the system shown in Fig. 3, each signal S has associated therewith an approach lighting relay AER controlled by traffic conditions in the section governed by the associated signal and in the section in the rear of such signal; and with a signal control relay DR controlled by trafiic conditions in the section governed by the associated signal and in the section in advance of such section. The approach lighting relay AER associated with one signal, and the signal control relay DR associated with the signal in the rear of such one signal, may be energized in series over a circuit governed by trafiic on the stretch, or as shown, these relays may be controlled over individual circuits. For example, relay AERZ associated with signal SDis represented as being energized over an obvious circuit extending from one terminal B of a suitable source of current, such as a battery not shown, through front contact 25 of relay TRE. the winding of relay AER2 and front contact 26 of relay TRD to terminal C. Relay DR associated with signal SE is energized over an obvious circuit extending from terminal B through front contact 2'! of relay TRD, the winding of relay DR and front contact 28 of relay TRE to terminal C.

The apparatus of Fig. '3 is so arranged as to cause each signal S to display a more restrictive indication should the signal fail to display an indication when conditioned to display its clear in dication. Also, the arrangement is such as to cause signal SE to display a more restrictive red indication in the event of a failure of either lamp Y of the two lamps constituting the permissive indication. The apparatus of Fig. 3 is arranged so that when section DE, the section immediately in advance, and the section immediately in the rear of section D-E are unoccupied, the apparatus is in its normal condition as represented in Fig; 3. In this condition of the apparatus, approach lighting relay AERI and signal control relay DR are energized, green lamp G of signal SE is energized over a circuit extending from terminal BX through front contact 8 of relay POR, front contact 29 of relay AERI, resistor 5, winding I5 of relay LRI. front contact 30 of relay DR, the filament of lamp G of signal SE and front contact I2 of relay POR to the other terminalCX; and one lamp Y of signal SE is energized over a circuit extending from terminal BX through front contact 8 of relay FOR, resistor 5, winding I9 of relay LE2, the filament of lower lamp Y of signal SE and front contact I2 of relay POR to the other terminal CX. The resistors function to limit the current flowing in the circuits of lamps G and Y of signal SE to a value insufiicient to cause such lamps to become illuminated, but sufficient to cause relays LRI and LE2 to be effectively energized. In this condi tion of the apparatus, signal SE is conditioned to display its clear aspect, and will do so in the event that a train enters a section in the rear of section DE to cause approach lighting relay AER! to be released. When this happens, back contact 29 of. relay AER! closes to complete a circuit extending from terminal BX through front contact 8 of relay POR, back contact 29- of relay AERI, front contact 3| of relay TRE, low resistance winding M of relay LRl, front contact 30 of relay DR, the filament of lamp G of signal SE and front contact 12 of relay POR to terminal CX. Winding I4 of relay LRI is proportioned to permit the current flowing in the circuit of lamp G of signal SE to assume a value sufficient to cause such lamp to become illuminated and cause signal SE to display its clear indication. In the event, however, that the filament of lamp G of signal SE fails or burns out under the conditions just assumed, relay LRI of course releases and causes signal SE to display its single caution or approach indication. This indication is displayed when upper lamp Y of signal SE becomes energized over a circuit extending from terminal BX through front contact 8 of relay POR, back contact 29 of relay AERI, front contact 3: of relay TRE, front contact 32 of relay DR, back contact 33 of relay LEE, the filament of upper lamp Y of signal SE and front contact l2 of relay POR to terminal CX. It is apparent, therefore, that when signal SE fails to display its clear indication when conditioned to do so, the signal is then automatically causedrto display amore restrictive indication due to the illumination of a single yellow lamp of the signal. 7

In the event that the section in advance of section DE is occupied while section DE and the section in the rear of section DE are unoccupied, relay DR associated with signal SE is then deenergized due to the-release of relay TRD, while relay AERl is picked up. In this condition of the apparatus, the upper lamp Y of signal SE is energized over a circuit extending from terminal BX.- through front contact 8 of relay FOR, front contact 29 of relay AERI, resistor 5, winding l5 of relay LRLback contact 30 of relay DR, the filament of upper lamp Y of signal and front contact l2 of relay POR to terminal CK; while the other or lower lamp Y of signal SE is energized over a circuit corresponding to that previously pointed out. If, now, a train enters the section in the rear of section DE to cause approach lighting relay AERI to release, signal SE is then caused'to display a singleyellow aspect or its approach indication due to the energization of the upper lamp Y of signal SE over a circuit extending from terminal BX through front contact 8 of relay POR", back' contact 29 of relay AERI, front contact 3| of relay TEE, low resistance winding 14 of relay LRI, back contact 30 of relay DR, the filament of upper lamp Y of signal SE and front contact l2 of relay POR to terminal CX. The value of current permitted to flow in the circuit of'lamp Y when winding I 4 of relay LRI is interposed therein, is sufficient to cause such lamp to become effectively energized and illuminated to thereby cause signal SE to display its approach-aspect.

The apparatus of Fig. 3' is arranged in such manner as to provide the-form of approachlighting that furnishes an illuminated indication for the signal. in the rear of the train, regardless ofwhether or not another train is following the first train. That is to say, when a train occupiessection DE and relay TRE is released, the approach lighting relay AERl also is released re-- gardless of whether the section in the rear of section DE is or is not :occupied, and under such conditions both lamps,Y of signal SE are illuminated to cause signal SE to display a doublecaution permissive indication. One lamp Y'of signal SE is energized under the assumed conditions over a circuit extending from terminal BX through front contact 8 of relay POR, back contact 29 of relay AERI, back contact 3| of relay TRE, front contact 20 of relay LRZ, back contact 32 of relay DR, winding H of relay LRI, back contact 30 of relay DR, the filament ofupper lamp Y of signal SE and front contact I!- of relay POR to terminal CX; while-the other lamp Y of signal SE is energized over a circuit extending from terminal BX'through front con-- tact 8 of relay POR, back contact 34 of relay" TRE, front contact I! of relay LRI, winding l8- of relay LE2, the filament of lower lamp Y of signal SE and front contact I2 of relay POR to terminal C. The magnitude of current permitted to flow through windings M and :8 of relays LR!- and LE2, respectively, in the circuits of the lamps Y of signal SE is suflicient to maintain such relays picked up and cause the lamps to be effectively energized and illuminated. 'It is to be noted that the circuit of each lamp Y of signal SE is carried through a' winding of its associated light-out relay and a front contact of the other light-out relay, with the result that should either.

lamp fail or burn out, its associated light-out relay LR is caused to release to open at its front contact the illuminating circuit for'the other yellow lamp. For example, if the upper yellow lamp" Y burns out or fails, relay LR! energized in'series' therewith releases to open its front contact ll interposed in the illuminating circuit of the other lower lamp Y. Relay LR2 may at this time be energized by current supplied through resistor 5 to winding 19 of relay LR2 and the filament of lower lamp Y, but with relay L-Rl released, lamp R of signal SE becomes illuminated over a cir-- cuit which extends from terminal BX through front contact 8' of relay POR, book contact 34 of relay TRE, back contact I! of relay LRI, the filament of lamp'R of signal SE, and frontcontact l2 of relay POR to terminal 02!. On'the other hand, if the lower lamp Y fails, relay LRZ is caused to release and open its front contact- 20 interposed in the illuminating circuit of the upper yellow lamp; Relay LRI is also released at thistime, thereby causing red lamp R to'becomeilluminated over the circuit previously. traced for this lamp, as well as over an alternate circuit which extends from terminal BX through front contact 8 of relay POR, back contact 29' of relay AERI, back contact 3| of relay TRE, back contact 29 of relay LRZ, the filament of lamp R of signal'SE and front contact l2 of: relay POR to terminal CX. It is' apparent, there-'- fore, that in the event of a failure of either lamp Y of signal SE when the signal is conditioned to:

display its double-caution permissive aspect, the signal isthen caused to display the more restrictive red aspect.

Fig; 4' represents the apparatus of Fig. 3 modified to incorporates, polarized signal control re-' lay PDR, preferably of the retained neutral type; energized over pole changing. contacts land 43- V of relay TRD and front contacts 4| and 42 of relay TRE, and which apparatus is arranged to provide a single yellow lamp reserve for the green lamp G of signal SE, and a single red lampR reserve for the double-caution permissive indication of signal SE. The circuit for each control relay PDR may include in series therewith the winding of the approach lighting relay AER associated with the signal in advance, or as shown in Fig. 4, each relay AER may be controlled over a separate circuit corresponding to the circuit pointed out for such relay in connection with the apparatus of Fig. 3.

The apparatus of Fig. 4 is in its normal condition, as represented in the drawings, when section DE, the section immediately in advance, and the section immediately in the rear are unoccupied. In this condition of the apparatus, relay PDR is energized by current of normal polarity and operates its polar contact members to their normal or lefthand positions. Winding l5 of relay LRI is energized over an obvious circuit extending from terminal BX through front contact 8 of relay POR, front contact 29 of relay AERI, winding 14 of relay LRI and front contact l2 of relay POR to terminal CX; while winding l9 of relay LR2 is energized over a circuit extending from terminal BX through front contact 8 of relay POR, resistor 5, winding IQ of relay LRZ, the filament of lower lamp Y of signal SE and front contact l2 of relay POR to terminal CX. Relays LRI and LR2 accordingly are effectively energized and picked up, but resistor 5 limits the current through lower lamp Y to a value insufficient to cause such lamp to be illuminated.

When the section in the rear of section D--E becomes occupied, and section D-E and the section in advance remain unoccupied, relay AER! releases and lamp G of signalSE becomes energized over a circuit extending from terminal BX through front contact 8 of relay POR, back contact 29 of relay AERI, winding 14 of relay;LRl, front contact 36 and normal polar contact 31-38 of relay PDR, the filament of lamp G of signal SE and front contact 12 of relay POR to terminal CX. Lamp G is effectively energized and illuminated, while relay LRI remains in its picked-up position. Should, however, the filament of lamp G fail or burn out, then lamp G becomes dark and relay LRI releases to complete a circuit passing from terminal BX through front contact 8 of relay POR, front contact 39 and normal polar contact 40- of relay PDR, back contact 42 of relay AERI, back contact 43 of relay LRI, the filament of upper lam-p Y of signal SE, and front contact l2 of relay POR to terminal OK. It follows, therefore, that if signal SE fails to display its clear indication when conditioned to do so, the apparatus of Fig. 4 functions to cause the more restrictive single yellow or caution indication to be displayed.

In the event that smtion D--E is unoccupied when the sections immediately in advance and in the rear are occupied, then relay TRD is released, relay PDR is energized by current of reverse polarity, and the upper lamp Y of signal SE is energized over a circuit corresponding to the previously traced circuit of lamp G but including reverse polar contact 3l44 of relay PDR and the filament of upper lamp Y in the place of normal polar contact 3l38 of relay PDR and the filament of lamp G, respectively. At such time, lamp Y is illuminated and relay LRlis picked up.

When section D-E and the section in the rear are occupied, relay PDR is released and both lamps Y of signal SE are illuminated. One lamp Y is illuminated over a circuit which may be traced from terminal BX through front contact 8 of relay POR, back contact 29 of relay AERI, winding l4 of relay LRI, back contact 36 of relay PDR, front contact 45 of relay LE2, the filament of upper lamp 4 of signal SE and front contact l2 of relay POR. The other lamp Y is illuminated over a circuit which passes from terminal BX through front contact 8 of relay POR, back contact 39 of relay PDR, front contact 46 of relay LRI, winding l8 of relay LR2, the filament of gized in series therewith releases to open its front contact 45 and thereby open the illuminating circuit of the upper yellow lamp, whereupon relay LRI also releases. Red lamp R of signal SE accordingly becomes illuminated over a circuit which extends from terminal BX through front contact 8 of relay POR, back contact 41 of relay PDR, back contact 48 of relay LRZ, the filament of lamp R and front contact [2 of relay POR to terminal CX. Back contacts 39 and 46 of relays PDR and LRI, respectively, are connected in series in a multiple path provided in the circuit of lamp R around back contacts 4'! and 48 of relays PDR and LRZ, respectively. In the event that the filament of the upper yellow lamp fails while the filamentof the other lamp remains intact, relay LRI energized in series with the upper lamp then releases to open its front contact 46 interposed in the illuminating circuit of the lower lamp, whereupon both yellow lamps become dark. Relay LR2, at this time, may be energized by current supplied to its winding I9 through resistor 5 and the filament of the'lower yellow lamp, but with relay LR2 released, lamp R of signal SE becomes illuminated over its circuit previously traced. 7

From th foregoing description, it is readily apparent that I have provided novel and improved signal systems incorporating means for providing light-outprotection in circuits utilizing a double-caution permissive aspect to indicate that a block is occupied, and also to provide a single caution indication in the event of a failure of the green or clear indication of the signal.

Although I have herein shown and described only several forms of railway signaling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within th scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described claim is:

1. In combination, a signal having a plurality of lamps a selected two of which when illuminated provide one indication, two relays one for each of said selected two lamps, means for at times energizing oneof said two lamps over a circuit including a winding of one of said two relays and a front contact of the other of said two relays and for simultaneously energizing the other of said selected two lamps over a circuit my invention, what I including a winding of said other relay and a front contact of said one relay, and means for energizing a third lamp of said signal over a circuit including a back contact of either of said two relays when said last mentioned means is interrupted due to a failure of the lamp filament of either of said selected two lamps.

2. In combination, a signal having a plurality of lamps a selected two of which when illuminated provide one signal indication, a first relay, means for energizing a third of said lamps over a circuit including a winding of said first relay, means controlled by said first relay for energizing a selected one of said two lamps when said firstmentioned means is interrupted due to a failure of the lamp filament of said third lamp, a second relay, means for at times energizing one of said selected two lamps over a circuit including a front contact of said first relay and a winding of said second relay and for simultaneously energizing the other of said selected two lamps over a circuit including a front contact of said second relay and another winding of said first relay,

a plurality of lamps and arranged to display a 0 single indication when a selected two lamps of the signal are simultaneously illuminated, the combination with such a signal of two relays one for each of said selected two lamps, means for energizing each of said two lamps over a circuit including a winding of its associated relay and at a level sufiicient to pick up the relay but not to illuminate the lamp, other means for at times energizing each of said two lamps over a circuit including the winding ofits associated relay and a front contact of the other relay and at a level sufficient to illuminate such lamp, and means controlled by said relays when released at-such times by a failure o'feith'er of said lamps for energizing a third lamp of said signal at a level 4 suflicient to illuminate said third'lam-p.

4. In a signal system of the class wherein a signal having a pluralityoflamps is arranged to 7 provide a distinctiveindication when a selected 7 7, two of such lamps are simultaneously energized, the combination with such a signal'of two relays one for each of said selected two lamps, means for constantly energizing each of said selected two lamps i'n'serie's with a winding of the associated relay at a level sufiieie-nt to pick up such 5;, relay but not to illuminate such lamp, means for at times additionally energizing each one of said selected two lamps over a circuit including a front contact of the relay associated with the other one of said selected two lamps and at a level s'ulficient to cause such lamp to be illuminated, and means controlled by said relays and eifective whenever said last mentioned means is interrupted by a failure of either of said selected two lamps, for illuminating a third lamp of said signal.

5. In a signal system of the class wherein a signal having a plurality of lamps displays a distinctive indication when a selected two of such lamps are simultaneously illuminated, the com- 70 bination with such a signal'of two relays one for each of said selected two lamps, means for normally energizing one of said relays in series with a third lamp of said signal at a level suifieient to pick up such relay but not to illuminate such T5 third lamp, means for at times energizing said one relay in series with said third lamp at an increased level sufficient to illuminate said third lamp, means controlled by said one relay when released at such times by a failure of said third lamp for energizing one of said selected two lamps at a level sufficient to illuminate such one lamp, means for normally energizing the other of said relays in series with the other of said selected two lamps at a level sufficient to pick up said other relay but not to illuminate said other selected lamp, means for at times simultaneously illuminating both of said two selected lamps, said one selected lamp being illuminated over a circuit including the winding of its associated one relay and a front contact of the other relay and the other selected lamp being illuminated over a circuit including a front contact of said one relay, and means controlled by said relays for energizing a fourth lamp of said signal should either of said relays be caused to release by a failure of either of said selected two lamps when said two lamps are conditioned to be simultaneously illuminated.

6. In a signal system of the class wherein a signal having a plurality of lamps displays a distinctive indication when a selected two of such lamps are simultaneously illuminated, the combination with such a signal of two relays one for each of said selected two lamps, means for normally energizing one of said relays in series with a third lamp of said signal at a level sufficient to pick up such relay but not to illuminate such third lamp, means for at times energizing said one relay in series with said third lamp at an increased level suflicient to illuminate said third lamp, means controlled by said one relay when released at such times by a. failure of saidthird lamp for energizing one of said selected two lamps at a level sufflcient to illuminate such one lamp, means for normally energizing the other of said relays inser'ies with the other of said selected two lamps at a level sufficient to pick up said other relay but notto illuminate said other se lected' lamp, means for at times simultaneously illuminating both of said selected twolam'ps each over a circuit including in series the winding of the associated relay and a front contact of-the other relay, and means controlled by said relays for energizing a fourth lamp of said signal should either of said relays be caused to release by a failure of either of said selected two lampswhen said two lamps are conditioned to be simultaneously illuminated.

'7. In a signal system of the class wherein a signal having a plurality of lamps is caused to display a distinctive indication when a selected two of such lamps are simultaneously illuminated, the combination with-such a signal of two relays one for each'of said selected two lamps, a circuit including a winding of its associated relay for normally energizing one of said selected two lamps at a level sufficient to pick up said relay but insufficient to illuminate said one lamp} a circuit for normally energizing the other of aid relays, circuit means including the winding of its associated relay and a front contact of the other relay for at times energizing each of said selected two lamps at a level suflicient'to illuminate such lamp, and circuit means controlled by said relays and rendered eflect'ive when said last mentioned circuit means is interrupted by a failure of either of said two lamps for energizing a third lamp of said signal at a level sufiicien't to illuminate such third lamp. r c

8. In a signal system of the class wherein a signal having a plurality of lamps is caused to display a distinctive indication when a selected two of such lamps are simultaneously illuminated, the combination with such a signal of two relays one for each of said selected two lamps, a circuit including a winding of its associated relay for normally energizing one of said selected two lamps at a level sufficient to pick up said relay but insufficient to illuminate said one lamp, a circuit for normally energizing the other of said relays, a circuit including a winding of said other relay for at certain times energizing a third lamp of said signal at a level sufiicient to illuminate such lamp, means controlled by said other relay when released at said certain times by a failure of said third lamp, for illuminating the other one of said selected two lamps, circuit means including the winding of its associated relay and a front contact of the other relay for at times energizing each of said selected two lamps at a level sufficient to illuminate such lamp, and circuit means controlled by said relays and rendered effective when said last mentioned circuit means is interrupted by a failure of either of said two lamps, for energizing a fourth lamp of said signal at a level sufiicient to illuminate such fourth lamp.

9. In a signal system of the class wherein a signal having a plurality of lamps is caused to display a distinctive indication when a selected two of such lamps are simultaneously illuminated, the combination with such a signal of two relays of the direct current type one for each of said selected two lamps, a source of alternating current and a source of unidirectional current, circuit means for normally connecting each of said selected two lamps in series with a winding of its associated relay to said alternating current source, said circuit means including asymmetrical units connected in multiple with the windings of each relay and a resistor for limiting the current to a value insufficient to illuminate the lamps but suflicient to pick up said relays in response to the half-wave pulses of current flowing therethrough, other circuit means for at certain times connecting each of said two lamps in series with a winding of its associated relay and a front contact of the other relay to said alternating current source, said other circuit means also including asymmetrical units connected in multiple with the windings of said relays and said windings being proportioned to permit current to flow having a value suflicient to illuminate such lamps, additional circuit means controlled by said relays and effective at said certain times when said other circuit means is interrupted due to a failure of either of said two lamps, for connecting a third lamp of said signal to said alternating current source in a circuit having a current flow therein of a value sufficient to illuminate said third lamp, and means responsive to a failure f power from said alternating current source for conditioning each of said circuit means to be connected to said unidirectional source, said asymmetrical units in said circuit means being arranged to oppose the now of current from said unidirectionalcurrent source.

10. In a signal system of the class wherein a signal having a plurality of lamps is caused to display a distinctive indication when a selected two of such lamps are simultaneously illuminated, the combination with such a signal of two relays of the direct current type one for each of said selected two lamps, a source of alternating current and a source of unidirectional current, means for normally connecting each of said selected two lamps in series with a winding of its associated relay to said unidirectional current source, said windings being proportioned to limit the current in said means to a value sufficient to pick up said relays but insufficient to cause illumination of said lamps, circuit means for at certain times connecting each of said two lamps in series with a winding of its associated relay and a front contact of the other relay to said alternating current source, said other circuit means also including asymmetrical units connected in multiple with the windings of said relays and said windings being proportioned to permit current to flow having a value sufficient to illuminate such lamps, additional circuit means controlled by said relays and effective at said certain times when said other circuit means is interrupted due to a failure of either of said two lamps, for connecting a third lamp of said signal to said alternating current source in a circuit having a current flow therein of a value sufficient to illuminate said third lamp, and means responsive to a failure of power from said alternating current source for conditioning each of said circuit means to be connected to said unidirectional source, said asymmetrical units in said circuit means being arranged to oppose the flow of current from said unidirectional current source.

HENRY S. YOUNG. 

